八肽胆囊收缩素激活钙离子通道和酪氨酸激酶诱导豚鼠心肌细胞内的游离钙增高

探讨八肽胆囊收缩素(CCK-8)对豚鼠单个心肌细胞内游离钙浓度(Ca2+]i的影响及其信号转导机制.Fluo 3-AM标记酶消化法分离的单个心室肌细胞,用激光共聚焦显微镜测定细胞内Ca2+]i的浓度.Ca2+]i的变化用荧光强度(Fi)和相对荧光强度(Fi/F0%)表示.实验结果如下(1)在含Ca2+1.0 mmol/L的Tyrode's液中,CCK-8(1～104pmoVL)均可引起Ca2+]i快速显著上升(P＜0.01).(2)用钙离子鳌合剂EGTA(3 mmol/L)和钙离子通道阻断剂nisoldipine(0.5μmol/L)预孵育心肌细胞5 min,CCK-8(102pmol/L)仅可引起Ca2+]i缓慢轻度上升(P＜0.01).(3)用非选择性CCK受体拮抗剂丙谷胺(proglumide 6μmo1/L)或酪氨酸激酶抑制剂genistein(1 μmol/L)预孵育心肌细胞5 min,则完全抑制CCK-8诱导的Ca2+]i升高(P＜0.01).CCK-8可通过激活其受体控制的Ca2+通道,引起Ca2+内流,诱导细胞内Ca2+释放,引起豚鼠单个心肌细胞内Ca2+]i上升,此作用可能由酪氨酸激酶介导.

Cholecystokinin octapeptide increases free intracellular calcium of guinea pig cardiomyocytes through activation of Ca2+ channel and tyrosine kinase

The aim of the present study was to explore the effect of cholecystokinin octapeptide (CCK-8) on Ca(2+)](i) and its signal transduction mechanism in isolated guinea pig cardiomyocytes. Ca(2+)](i) was measured by laser scanning confocal microscopy in single ventricular myocytes which were dissociated by enzymatic dissociation method and loaded with Fluo 3-AM. The changes in Ca(2+)](i) were represented by fluorescent intensity (F(i)) or relative fluorescent intensity (F(i)/F(O)%). The results obtained are as follows. (1) In the normal Tyrode's solution containing 1.0 mmol/ L Ca(2+), CCK-8 (1-10(4) pmol/L) elicited a rapid and marked increase in Ca(2+)](i). (2) When cardiomyocytes were pretreated with the Ca(2+) chelator EGTA (3 mmol/L) and Ca(2+) channel antagonist nisoldipine (0.5 micromol/L) for 5 min, CCK-8 (10(2)pmol/L) caused a slow and small increase in Ca(2+)](i) (p< 0.01). (3) Pretreatment with the nonselected CCK- receptor (CCK-R) antagonist proglumide (6 micromol/L) or the tyrosine kinase inhibitor genistein (1 micromol/L) for 5 min could inhibit the increase of Ca(2+)](i) induced by CCK-8 (10(2) pmol/L) (p<0.01). The results suggest that CCK-8 increases the Ca(2+)](i) via activating the receptor-operated Ca(2+) channel and eliciting the influx of Ca(2+) in isolated guinea pig cardiomyocytes, in which tyrosine kinase may be involved.